Install Zabbix with network monitoring

Install Zabbix server with tutorial for your operating system (google it).
Install zabbix-agent and network monitoring script:

For Debian 9 agents:

apt-get install zabbix-agent vnstat bc unzip zip dos2unix -y && vnstat -u -i ens3 && mkdir /etc/zabbix/script && cd /etc/zabbix/script && wget http://skalski.pro/files/files/zabbix_network_monitor/bandwidth.zip && unzip bandwidth.zip && chmod +x * && dos2unix *.sh && wget http://paste.ots.me/563447/text && mv text /etc/zabbix/zabbix_agentd.conf && nano /etc/zabbix/zabbix_agentd.conf

Edit Hostname, Server and ServerActive:

Hostname=yourvpsname
Server=yourzabbixserverip
ServerActive=yourzabbixserverip

Restart agent:

systemctl restart zabbix-agent

Add CRON:

* * * * * sh /etc/zabbix/script/update.sh

Network monitoring plugin for Zabbix server GUI:
http://skalski.pro/files/files/zabbix_network_monitor/Network-For-Linux.zip